Nuclear, nucleolar and chromosomal protein antigens and their complexes with nucleic acids will be investigated in normal and malignant cells of human colon. The antigens will be isolated and extensively characterized in several tissue cultured human colonic carcinoma cell lines as well as in normal colonic mucosal specimens obtained by surgery. Antigens specific for normal or malignant cells will be studied in terms of their relationships to the DNA in transcriptionally active, inactive, replicating and DNA repair undergoing chromatin. Cell-specific antigens will be localized by conjugated antibodies method (fluorescent or peroxidase-antiperoxidase) in an attempt to develop histoimmunochemical methods for the detection of malignant and possible pre-malignant cells in frozen sections of human colon. Syrian hamsters will be employed in experiments on molecular mechanisms leading to qualitative changes (detectable immunologically) of nuclear proteins during experimental colorectal carcinogenesis. Attempts will be made to correlate the genomic distribution of the cancer-associated antigenic sites with the interaction sites of chemical carcinogens.